Lab talk

Jul 7, 2011

Thin-film solar: low-cost synthesis of CZTS nanocrystals

A low-cost route for synthesizing copper zinc tin sulfide (CZTS) – a promising material for thin film solar cells – and other polynary semiconductor nanocrystals has been reported by a China-US team. According to the group, the approach offers significant potential for large-scale processing. The researchers selected CZTS as their first candidate because the material holds the potential of reaching a similar efficiency to CIGS and thanks to the lower price and environmental impact, and greater availability of the starting components.

In this route, simple inorganic salts that replace expensive organic metal compounds were chosen as the metal source. These salts are dissolved in a polar solvent. Next, sulphur and alkyamine dissolved in a non-polar solvent are injected into the polar solution at high temperature and stirred vigorously. Dispersed microdrops form immediately.

The alkyamine facilitates transfer of the metal ion from the polar solvent to the non-polar solvent. Nanocrystal nucleation and growth occur within the microdrop. As a result, the nanocrystals are well dispersed in the non-polar solvent. The polar solvent can be reused in new, subsequent synthesis cycles because the metal ions are completely transferred to the non-polar solvent.

About the author

The study was conducted by researchers from the Key Lab of Excited State at Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP), CAS, China. Dr Xiuying Wang is a postdoctoral fellow at CIOMP, China. Prof. Zaicheng Sun leads a group that focuses on semiconductor nanocrystal PV devices and the localized surface plasmon resonance of metal nanostructures. Prof. Daniel M Boye is a professor of physics in the Physics Department at Davidson College, US. The research group is led by Prof. Jialong Zhao. The research goal of the group is to explore the photophysics of quantum-dot LED and PV devices.